1 /* 2 * Copyright (c) 2006, 2016, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package com.sun.source.util; 27 28 import com.sun.source.tree.*; 29 30 /** 31 * A TreeVisitor that visits all the child tree nodes, and provides 32 * support for maintaining a path for the parent nodes. 33 * To visit nodes of a particular type, just override the 34 * corresponding visitorXYZ method. 35 * Inside your method, call super.visitXYZ to visit descendant 36 * nodes. 37 * 38 * @apiNote 39 * In order to initialize the "current path", the scan must be 40 * started by calling one of the {@code scan} methods. 41 * 42 * @author Jonathan Gibbons 43 * @since 1.6 44 */ 45 public class TreePathScanner<R, P> extends TreeScanner<R, P> { 46 /** 47 * Constructs a {@code TreePathScanner}. 48 */ 49 public TreePathScanner() {} 50 51 /** 52 * Scans a tree from a position identified by a TreePath. 53 * @param path the path identifying the node to be scanned 54 * @param p a parameter value passed to visit methods 55 * @return the result value from the visit method 56 */ 57 public R scan(TreePath path, P p) { 58 this.path = path; 59 try { 60 return path.getLeaf().accept(this, p); 61 } finally { 62 this.path = null; 63 } 64 } 65 66 /** 67 * Scans a single node. 68 * The current path is updated for the duration of the scan. 69 * 70 * @apiNote This method should normally only be called by the 71 * scanner's {@code visit} methods, as part of an ongoing scan 72 * initiated by {@link #scan(TreePath,Object) scan(TreePath, P)}. 73 * The one exception is that it may also be called to initiate 74 * a full scan of a {@link CompilationUnitTree}. 75 * 76 * @return the result value from the visit method 77 */ 78 @Override 79 public R scan(Tree tree, P p) { 80 if (tree == null) 81 return null; 82 83 TreePath prev = path; 84 path = new TreePath(path, tree); 85 try { 86 return tree.accept(this, p); 87 } finally { 88 path = prev; 89 } 90 } 91 92 /** 93 * Returns the current path for the node, as built up by the currently 94 * active set of scan calls. 95 * @return the current path 96 */ 97 public TreePath getCurrentPath() { 98 return path; 99 } 100 101 private TreePath path; 102 }